1998 * IX * 1

SISUKORD

http://agrt.emu.ee/pdf/1998_1_sisukord.pdf

TEADUSTÖÖD

K. Annuk, R. Kalmet.

Rohunditest looduslikel ja kultuurrohumaadel

3

On Motley Grasses on Natural and Cultural Grasslands. Species composition of motley grasses growing on natural grasslands is extensive, therefore the group properties presented by them are heterogeneous. That is why chemical composition and nutritional value of legumineous and graminaceous grasses have been studied more thoroughly than that of motley grasses. Among motley grasses, beside toxic plants, very valuable dietefic plants can be found. Motley grasses provide for a manifold composition of grass-stands.

The importance of motley grasses in the yield of grasslands depends on the place of growing, soil supply of germinating seeds (Table 1) and their spreading possibilities, agro-technics of foundation of cultural grasslands (Table 2), maintenance and regimes of use of grass-stands (Tables 3…5).

Among motley grasses species can be found whose macro- and micromineral composi-tion (Tables 6…8), protein and carotene content, amino acids composition and energy con-centration (Table 8) may exceed the respective characteristics of breeding cultivars of graminaceous and legumineous grass plants.

Thus, a conclusion can be drawn that grass-stands founded as new sowings on the basis of a few species may result one-sided as fodder. It should be taken into account that despite of a good chemical composition of dry matter and nutritional value of sting nettle and dan-delion, these species are considered weeds due to their capacity of mass spreading.

Seed yield and quality of late red clover variety 'Jõgeva 205' and the relation of these indicators with growing time weather conditions from 1946 to 1995. Late red clover (Trifolium pratense subvar. serotinum Witte) variety 'Jõgeva 205' (2n) was bred at Jõgeva Plant Breeding Institute from 1929 to 1940. The variety is still in use.

The maintenance breeding and basic seed production of the variety has taken place at Jõgeva (58°45' northern latitude, 26°24' eastern longitude, mean annual air temperature 4.4° C, amount of precipitation 655 mm) and it has been consistent. Correlations between the seed yield and quality indices of the breeder seed of variety 'Jõgeva 205' and growing time weather conditions during 50 years (1946…1995) are discussed in the current study.

The potential seed yield capacity of the late red clover variety 'Jõgeva 205' is high (>600 kg/ha), but realization of it depends to a great extent on weather conditions during growing and harvest time. With adverse weather conditions no management practice can assure satisfactory seed yield. Arising from that, the seed yield of late red clover variety 'Jõgeva 205' may fluctuate about 200 times (Table 1), irrespective of the growers’ will which is approximately 100 times more than for cereals. Need for creation of (state) seed reserve fund is determined by the amplitude of seed yield fluctuation of the species (variety). The Republic of Estonia has created it for more important cereals, but unfortunately it is still missing for forage legumes.

As an average of 50 years (1946…1995) late red clover 'Jõgeva 205' yielded 191 kg of seed per hectare. Under Estonian conditions the likelihood of getting low seed yields (<100 kg/ha) is 32%, getting of satisfactory seed yields (100…250 kg/ha) is 38% and getting of good seed yields (>250 kg/ha) is 30%. Low and high seed yields may occur in several years in sequence. To arouse interest and to mitigate the production risk of seed producers, the Republic of Estonia has to start a (voluntary) insurance system of the seed fields of forage legumes.

Trend of seed yield decrement of the variety 'Jõgeva 205' turns to seed producers’ attention to the requirement to work more on high seed yields on selection nurseries.

Among the agrometeorological factors heat and sunshine have positive impact on the seed yield of late red clover 'Jõgeva 205', while frequent and plenty rainfalls have negative effect (table 2).

1000 seed weight of the variety 'Jõgeva 205' was 1.74 g on the average of a number of years (n=47), the figure tends to rise. Warm, sunny July assured the higher 1000 seed weight, while rainy July, on the contrary, decreased it. Mean germination of the seeds grown at Jõgeva Plant Breeding Institute was 90% (n=48). High precipitation (especially in August) decreases germination.

The content of hard seeds present in the seed lots was 17% (n=47); during 11 years the content of hard seeds accounted for more than 20%. It was not possible to establish strict correlative relations between the content of hard seeds and agrometeorological factors during the growing season.

The present article deals with the dependence of seed yield and its quality on the weather conditions during growing season on harvest year. Seed yield of red clover as perennial crop plant depends on many additional circumstances such as the weather in seeding year, overwintering conditions, occurrence of diseases, pests and weeds and effi-ciency of their control, success of bumble-bee nesting last year, amount of overwintered young bumble-bee queens, quality of the work, choice of harvest time, etc.

Due to of big harvest-losses, losses in preliminary and final cleaning and other reasons, the actual and biological seed yields of late red clover may differ essentially.

The quality indicators of seed yield presented in the study are adjustable (to some extent) by cleaning machines.

On the basis of above-mentioned reasons high (r=>0,66) correlative relations were not found between the seed yields, quality and weather conditions.

http://agrt.emu.ee/pdf/1998_1_bender.pdf

J. Bergström, K. Ling, B. Pehrson.

Mõningaid andmeid Eesti lehmade seleeniga varustatuse kohta

22

Some data on the selenium status of dairy cattle in Estonia. Twelve randomly selected herds were used for charting the selenium status of Estonian cattle. In seven herds no extra selenium was given, while five fed a selenium supplemented mineral feed. The selenium supplementation was, however, very moderate.

Blood samples were taken for determination of glutathione peroxidase (GSH–Px) in erythrocytes from 7–15 lactating cows, 1–5 dry cows and 4–5 heifers per herd. Milk samples were taken from the lactating animals for determination of selenium and GSH–Px activity.

All animals in the unsupplemented herds had GSH–Px values indicating severe selenium deficiency. When transformed to selenium concentration in whole blood the herd means corresponded to 15–25 μg/l. With one exception the herd means of the supplemented herds were also too low. The herd with a reasonably normal blood selenium status fed more selenium supplemented mineral feed than the others.

The selenium concentration in milk was very low irrespective of whether there had been a selenium supplementation or not (4.5 and 5.1 μg/l, respectively). This was partly supposed to be caused by a low degree of supplementation, and partly by the fact that selenite – at least in comparison to organic selenium compounds – has been found to be relatively inefficient for increasing the selenium concentration of milk.

There was a significant correlation between the selenium concentration and the GSH–Px activity in milk, but the activity of the enzyme was extremely low.

The investigation shows that Estonia should be included among the countries which are highly selenium deficient.

The Effect of the Single Strain Starter Cultures and the Thermophilic Mixed Culture on Technological Parameters and Quality of Emmental Cheese. The effect of the thermophilic lactic acid and the propionic acid single strain starter cultures and the thermophilic mixed starter culture on technological parameters and quality of Emmental cheese was studied.

pH of vat milk, time of coagulation, pH of whey and operations durability from milk coagulation to cooking did not depend on relation between thermophilic single strains in starter and on kind of strains. The mesophilic starter determined in this period the change of acidity. The stir-out time of curd particles was 4.6–4.8 min. shorter, pH of 24 hours old cheeses 0.11–0.12 unit lower and moisture content 1.2–1.5% lower than in cheeses, made with the thermophilic mixed starter TMB. Differences on same regime of temperature were caused by stable relation between thermophilic lactic acid streptococci and lactobacilli of monocultures starters and their higher activity to produce lactic acid on stir-out of curd particles and on pressing of the cheeses.

Upon making the thermophilic mixed bulc starter TMB, the relation between streptococci and lactobacilli changed and the activity of cultures was hardly controllable. Differences of pH and moisture content between the test and control cheeses in warm room ripening disappeared. The exchange of propionic acid bacteria cultures did not affect cheesemaking technological parameters, pH of 24 hours old cheeses and the moisture content of cheeses.

The flavour and arome, consistence and texture of 3 month old cheeses, made with the thermophilic single strain starter cultures were essentially better than those of cheeses made with the thermophilic mixed starter culture TMB.

Using of propionic acid bacteria cultures which grew well with thermophilic and mesophilic lactic acid starter cultures improved essentially the texture, flavour and arome of cheeses.

Therefore, the types of Streptococcus thermophilus and Lactobacillus helveticus, the relation between them, their activeness and the use of propionic acid bacteria culture suitable to grow with them and with Lactobacillus casei were essentially important to improve the quality of Emmental cheese.

http://agrt.emu.ee/pdf/1998_1_elias.pdf

K. Kask, H. Jänes.

Eesti ploomisordid

34

The Estonian plum cultivars. The reported inventory of plum cultivars of Estonian origin include the cultivars which have the author's certificate and also these which are appreciated in other ways: included into the list of plum cultivars (officially recommended for growing in Estonia), or officially taken for testing in state fruit cultivar testing farms.

The entire list of the Estonian plum cultivars includes 23 cultivars. Some of them have mainly historical relevancy and have been preserved as plant genetic resources for future generations of mankind. The most valuable cultivars for plum producing in Estonia at the present time are underlined: 'Amitar', 'Ave', 'Esloni Varane', 'Hiiu Sinine'*, 'Julius', 'Kadri', 'Karksi', 'Liisu', 'Märjamaa'*, 'Noarootsi Punane'*, 'Norgen', 'Polli Munaploom', 'Polli Viljakas', 'Pärnu Sinine'*, 'Suhkruploom', 'Tamme Sinine'*, 'Tartu Kaunitar', 'Tartu Kollane', 'Tartu Punane', 'Tartu Värviline', 'Vikana', 'Vilmitar' and 'Vilnor'. 5 of these are landraces (shown with asterisk), including two large fruited bullace cultivars. 4 cultivars are bred by an amateur breeder Aleksander Kurvits at Tartu in the middle of the 20th century. All the other 14 cultivars are bred by the professional state breeding programme started in 1945 at the Polli Horticultural Institute in southern Estonia: the breeders are Julius Eslon (1894…1982), Arthur Jaama (1914…1995) and Eevi Jaama (b.1926).

In the official “cultivar list” recommended for growing in Estonia, 65% of cultivars are of Estonian origin. The Estonian plum cultivars have great relevancy for plum production also in Latvia and an interest for growing of some cultivars has arisen in Lithuania.

Morphological and biochemical characteristics of alfalfa crown. The morphological and biochemical constitution of alfalfa crown depending on a genotype charac-teristics and cutting regime in the fall of seeding-and 1st production-year has been studied. Fourteen alfalfa cultivars of different origin (of them two Estonian, one Swedish and eleven USA) and winter hardiness (three winter sensitive, three medium winter hardy and eight winter hardy) were evaluated during 1995…1996.

Two experiments were established at 22nd and 23rd of May 1995 and 1996, respectively in loamy Podzoluvisol soil (content of organic matter in 0…20 cm soil layer was 2,80…3,20%, total nitrogen and available potassium contents were 0,14…0,15% and 74,3…86,9 mg/100 g, respectively, and pHKCl was 6,2…6,4). Experiment 1 (established at 1995) included two different types of alfalfa cultivars – local Medicago varia Mart. Type ‘Karlu’ and Swedish Medicago sativa L. type ‘Pondus’. Experiment 2 (established at 1996) included 14 alfalfa cultivars (two of them Medicago varia and other twelve Medicago sativa).

During the seeding-year two-cut harvesting system was used. Harvests were done in July and beginning of October at the vegetative stage of development of alfalfa. In the production-year (Experiment 1 only) two-and three-cut system (first cuts at the bud and full flowering stage, respectively) with five different last cut time (cuts were done from the end of August to the beginning of October) were used.

To characterize the germplasms, 24 randomly selected plants from each cultivar sepa-rated from the soil at the beginning of October were tested. The methods of measuring the plant crown, tiller and tap root morphological (number, length and diameter of tillers on the basal level – 2 mm upon the crown start, weight and length of crown and diameter of the tap root on the basal level – 2 mm below the crown start) and biochemical characteristics of the crown (DM content, total nitrogen and sugar content by the Kjeldahl and Potshinok, respectively) were used.

The results of investigation we could be summarized as follows:

Local alfalfa (Medicago varia type) cultivars exceeded foreign ones for relatively heavy and long crowns and high DM, total nitrogen and sugar content in crown tissues at the beginning of October in seeding-year.

Though clear differences between foreign cv. were observed, the data badly corre-lated with winter hardiness. The exceptions were only dimensions of basal tillers (length and diameter) which appear to be larger in winter sensitive than winter hardy cultivars.

In the autumn of the 1st production-year (Experiment 1) morphological and bio-chemical characteristics of crowns depended on harvesting schedules. There was a small difference between ‘Karlu’ and ‘Pondus’ alfalfa if 2-cut harvesting regime was used (the exceptions were number of tillers – ‘Karlu’ has more axillary and less basal tillers than ‘Pondus’). By increasing the number of cuts, the number of tillers per crown increased nearly twice and a tendency of an increase in the length of tillers was observed in ‘Karlu’ alfalfa but not in ‘Pondus’.

The tendency of decreasing of many characteristics of alfalfa crowns was noted if the last cut was done in the 1st week of September.

Efficiency of milk cooling by reservoir cooler MKA 2000L-2A and tankcoolers in farms. The Reservoir Cooler MKA 2000L-2A is a low-price (15 Estonian crowns/l) milk cooler, but its capacity (2000 l) is too small for large-scale farms, cools bulky milk too slowly in the farms of 200 and 300 cows, lacks units of heat recovery and automatic washing and needs large floor space for utilization as large-scale farms must use 2…4 units. The Reservoir Cooler is suitable for cooling milk in cattle-sheds for 100 cows.

New effective milk cooling tanks are of great importance in production of low bacterial count of milk as the increase of bacterial count of milk during cooling and storing in these tanks is avoided. Temperature of milk is at the end of the morning milking 4…6 °C and milk cools down to the temperature of 4 °C within 0.1…0.5 hours. All coolers satisfy the milk temperature and cooling duration requirements of European Communities and Standard ISO 5708, established for milk coolers.

Depending on the size of cattle-shed a milk cooling tank of corresponding capacity, must be used under consideration that it must enable to transport milk from farm to dairy if necessary, every other day. There has to be supply of sufficiently hot (60 °C) water in the farm for washing the tank because automatic cleaning units except cleaning unit of tank KT 5000 do not warm up washing solution.

http://agrt.emu.ee/pdf/1998_1_must.pdf

VÄLISAUTORID

K. Tiilikkala.

Kartulinematoodi Globodera rostochiensis integreeritud tõrje Soomes

59

Integrated control of potato cyst nematode, Globodera rostochiensis, in Finland. The effect of crop rotation on Globodera rostochiensis (Wollenweber, 1923) and potato yield were studied in 1981…1991 in southern Finland. Six different cropping systems were tested. In the plots with potato monoculture, the tuber yield decreased from 35 to 4.6 t ha-1. Cropping systems with potato once in 5, 4 or 3 years maintained the yield at the original level. Continuous growing of susceptible potato raised the population density of the nematode from 0.1 to 265 eggs g-1 soil in four years. After that the density fluctuated between 25 and 136 eggs g-1 soil. The nematicide treatments (oxamyl) did not control nematode multiplication but prevented yield losses. Growing of resistant (H1) potato reduced the nematode population by 80% and a non-host crop (oats) reduced it by 60% on average. The cropping system that can be recommend is potato once in three years with a resistant and susceptible cultivar grown alternately. No nematicide is registered no needed for control of potato cyst nematode in Finland.